Tuesday, 21 October 2014

Libre FGM v Enlite CGM

Welcome back. I hope you've got a nice cup of tea and a biscuit. This isn't a short one and you may need a suitable hypo-treatment ready in case the reading sends you low! And if you don't have diabetes just grab yourself a biscuit anyway, you deserve it.

First up I need to be very clear. I’m comparing an
apple with a pear here. The Freestyle Libre is being marketed as a Flash
Glucose Monitor that should be used to reduce the need for finger prick blood
testing. It is NOT being promoted as a Continual Glucose Monitor.

However…. For
me the lines are a little more blurred (time for a bad Robin Thick song?) as
the on screen display does show a line of blood glucose readings taken every
minute and averaged every 15. It’s measuring the same interstitial fluid that
my Enlite sensors use and I have to buy it privately, like I do for my CGM.
There’ll be corporate and licencing reasons I’m sure for Abbott to invent this
new terminology and this may become clearer over time. Or maybe it’s to make
themselves unique in the market? Who knows. Either way, to me it behaves more
like a CGM than a BM stick machine (off of the 80s) so my comparison is based
on that. The differences may become clearer as the review progresses below.

As I use a Medtronic Veo pump the Enlite sensor
utilises the screen of my pump to display all readings and graphs whereas the
Libre has it’s own handheld reader with display.

So let the comparison begin...

Cost (all prices ex-VAT)

Libre - Starter kit containing reader and two sensors £133.12. Reader is guaranteed for two years though should last longer. Subsequent sensors £48.29. 1st year cost = £1292.08 or £3.54 / day

Enlite

Transmitter and charger for £490 plus sensors which cost either £275 for 5 or £525 for 10. Transmitter lasts approximately 12 months and costs £350 to replace.

1st year cost = £3640.00 or £9.97 / day

Comparison

This is a hands down winner for the Libre. As a first
time user the initial commitment for four weeks of use is £133 compared to £765
for the Enlite. Postage costs for the Libre may come into play but as these are
unconfirmed and with rumours of a subscription discount these were ignored.

To be clear, over £1k a year isn’t cheap but it’s
certainly closer to affordable for occasional use with a lower initial outlay.

As an additional point, late last year Medtronic ran a
promotion where they gave you the transmitter and charger for free with your
first order of 5 sensors. Then the fourth box of five was also free after
paying for two more by the end of this month. Maybe this will be repeated for
new customers?

Score: Libre 4/5 Enlite 2/5

Calibration

Libre

Calibration is done in the factory at point of
manufacture. After this no further calibration is needed.

Enlite

After insertion the first calibration is done after
two hours. This is repeated every twelve hours of use. For most accurate use
it’s best to calibrate at a period of relatively steady blood glucose.
Obviously this can be tricky to achieve sometimes but in reality it’s normally
possible. I usually try to find a point after about 10 hours onwards.

Comparison

Another easy win for the Libre. The lack of any need
to calibrate the sensor meant it was up to speed after one hour rather than two.
As there was no need to recalibrate twice a day the challenge for finding a
winner in this segment was a little too easy.

Score: Libre 5/5
Enlite 3/5

Size and Appearance

Libre

For the Libre transmitter it’s easiest to describe it
as a white plastic disc approximately the size of a £2 or €2 coin. The
adhesive is entirely on the underside of the transmitter and for me this held
tight for the full two weeks (more on this later). The probe is underneath the
transmitter and is entirely hidden. The receiver can be described as the size
of a small light mobile phone with one small button on the front and a colour
touchscreen display. Charging is via a supplied, detachable USB cable.

Enlite

The Enlite transmitter is a similar size to the Libre
although about twice the height at its largest. The transmitter plugs into the
sensor which is underneath a small (5p size) piece of clear plastic. The whole
device is then secured using adhesive tape that sticks to the body and wraps
over the transmitter. In addition to this some more (provided) dressings are
used to secure the transmitter in place. When not in use the transmitter
‘docks’ in a charging device so that it is fully charged when in
use.

Comparison

As can be seen from the photos the ‘attractiveness’ of
the part stuck to your body varies between the two. The Libre could easily be
mistaken for a smoking patch and if you are more careful with its location than
I was, it can be easily hidden by a t-shirt sleeve. The Enlite is slightly
larger and more resembles a medical attachment. Having said that the clean
lines mean it isn’t overly ugly.

Score: Libre 5/5
Enlite 4/5

Setting Up / Insertion

Libre

To insert the Libre you place the applicator on the
skin and push down. The Libre is placed on the skin and a very small needle with
the metal sensor filament inside goes under the skin and then very quickly out
again. In a room of five people with diabetes who were trying out the sensor
none of us felt any pain on insertion. It was a surprisingly pleasant experience.
After this the first scan with the reader is done and a one hour countdown is
started. The accuracy of the sensor for the first 24 hours is not expected to
be as good as after that but I found no problems almost from the start. The
biggest negative for me on the set-up was the amount of hard plastic used in
the packaging and casing. This is probably necessary due to the factory
calibration but it seems a little wasteful.

Enlite

Insertion of the Enlite sensor uses the reusable
inserter. After placing the sensor into the inserter, place it against the
skin, press the button, release the button and hold for five seconds then
repress the button and lift off carefully. The needle is then left behind and
manually pulled out after putting the inserter down. There is a slight pain on
insertion that is similar to a painful injection or set change. After securing
down the sensor the Bluetooth transmitter is connected and secured with more
tape.

Comparison

The Enlite may be more environmentally friendly but sadly
the slight pain when compared to the Libre again puts it second in a two horse
race.

Score: Libre 4/5
Enlite 3/5

Ordering

Libre

All ordering for Libre is done using their online
shopping site that has now gone live. You can have a look here but please come
back if you click through to it! There is no need for any medical professional
approval for this device. This may be because of its role as a finger prick
replacement rather than as a CGM.

Enlite

Medtronic now have an online shop here where you can
order your CGM supplies once you’ve registered with them. If you are new to CGM
then you will require a letter from your doctor or nurse confirming that they
are happy for you to buy the device and will provide training for the first
insertion.

Comparison

Both systems appear easy although in fairness I have
used neither. The Libre was given to me at a previously mentioned meeting and for the
Enlites I’ve previously called the very nice people on their helpline. The need for
medical approval means a mark off for Enlite though.

Score: Libre 5/5
Enlite 4/5

Alerts

Libre

Alerts are where the Libre starts to behave like a
finger prick blood glucose test machine. As it will only pass the data from the
sensor to the reader when it is flashed. Any warnings of high and low are based
on the latest number available. An arrow on screen will indicate if this is going
up or down. Useful for easy reference. But that’s where the alerts stop. This
is an alert-free machine.

Enlite

Step forward Mr Medtronic it’s time to earn your
stripes! The Medtronic has advanced forecasting functions that work in
partnership with the Veo pump. I can set alerts to warn me if my readings are
dropping and rising quickly and also if upper or lower thresholds are set.
Timing controls mean that during the day my lower alerts are lower than at
night and my upper alerts are also slightly higher to take into account my
occasionally large post meal spikes. At night I run a much narrower band as
generally my levels are fairly steady when I’m asleep. Although I do not use
the predictive alerts as my hypo awareness is relatively good the slight nudge
I get when I hit a lower number of 3.9 is useful to just check that I’m aware
of my technical hypo and am treating it. Another feature of the Veo / Enlite combination, that is currently unique, is low-glucose-suspend when a low reading is reached. This
means that as well as the repeated audible and/or vibrating alarms the delivery
of insulin can be chosen to suspend to prevent a person with a dangerously low
blood sugar from receiving any more insulin. This is another feature that I do
not use but I have spoken with others who have used it. It can be potentially
useful for those who live alone and do not have anyone to check on them in the
morning.

Comparison

The CGM features of the Enlite win hands down here.
Before signing this section off though it’s useful to mention alarm fatigue. As
I mentioned below I don’t have all alerts on all of the time as repeated
unnecessary warnings can become so annoying that useful ones are ignored. The
Libre obviously doesn’t have this problem as it requires the wearer to actively
pull their readings instead of having them fed to the pump display.

Score: Libre 1/5
Enlite 4/5

Software

Libre

The software supplied with the Libre produces several
useful reports to show trends and highs and lows. Abbott are promoting the use
of the Ambulatory Glucose Profile (AGP) that it hopes will become a medical
standard. It is also possible to download a csv file of up to 90 days readings for
your own analysis. Every time the sensor is ‘flashed’ the reader downloads the
latest data to add to that already downloaded. Once 90 days worth of data is
downloaded it replaces this with new data. The reports that are run are based
on this flashed data. When created the reports are PDF files that are
created on the fly. It is not possible to create a report without the reader
being connected to your PC or Mac. A consequence of this is that reports cannot
be made of data that is over 90 days old unless you have downloaded the raw
data and create your own reports using Excel or another piece of software. Is
this a problem? I’m not sure. I’ll leave you to ponder that.

Enlite

The software the Enlite uses is through the Medtronic
Carelink website. As the data is coming from the pump it can also plot your
insulin usage and shows any finger prick tests taken using the
Bluetooth-connected blood test machine. The graphs are all very similar but the
addition of the insulin amounts showing boluses and basals is good extra feature. Once
the data is downloaded it is stored on the Carelink site for a very long time
(my data goes back to when I started pumping in 2011) and even if the pump is
changed the data remains and carries through in to newly generated reports. The
biggest downside for the Carelink software (apart from not working on Mac OS10
upwards) is that it is a reduced down version of the reports available to your
doctor or DSN when you go to see them. My hospital is predominantly Medtronic
and so data downloads are done when appointments happen and we analyse the
detailed charts together after I’ve done a little prep beforehand using the
much smaller ones.

Comparison

Two useful bits of software although the Medtronic
option wins for storing all the data online for access at any time from any PC
(or older Mac) without having to connect anything.

Score: Libre 3/5
Enlite 4/5

Screen Display

Libre

The screen on the Libre is very nice. Full colour and
touch sensitive makes using it very easy for me. How that works for those with
less sense of touch or finger control I’m not sure. The figures shown after
flashing are easy to read and in social circumstances it’s a very subtle
process that looks like someone just checking the time on their phone.

Enlite

A slight step backwards here for the Enlite. As it
uses the Veos screen which has been around for nearly ten years the age is
starting to show. It’s a monochrome display with a background light available
for when it’s dark. Due to screen size the graphs produced are relatively small
and hard to read. Having said that though they can be changed to show either 3,
6, 12 or 24 hour periods and also give a hard to read indication of basal rates
in those times. The key number which is the latest reading is easy enough to
spot though.

Conclusion

The Libre wins on ease of viewing but the Enlite runs
it closes because of the extra graphs

Score: Libre 4/5
Enlite 3/5

Accuracy

Libre and Enlite

And here’s where it starts to get to the important
bit. Accuracy has to be the key deciding factor in any comparison of a machine
that tests glucose in the body. During my six day direct comparison test both
machines had good accuracy for the duration. Previously I’ve experienced
occasional problems with the Enlite but none of that was visible here. The
difference came down to speed. For reasons unexplained by Abbott I found in this study
the delay between BG readings and the number on the Libre sensor was around 7 mins
with the Enlite following another 6 minutes later. It’s only fair to point out
the Enlite was on my stomach whereas the Libre was on my arm. Could this
account for some of the delay?

Another reasoning could be the frequency of the readings.
The Libre takes a reading every minute and if it’s changed since the last flash
it will update the number on the screen when it is flashed. The Enlite updates
the number shown every five minutes. If I’m trying to track a hypo treatment
those five minutes can last a long time.

The Libre claims to have a higher clinical accuracy
level than the Enlite and whilst this was slightly evident it wasn’t so much
that it was a reason to doubt the Medtronic product.

The winning factor here has to be the minute by minute
updates that are possible with the Libre and also that, in my limited
comparison, the numbers were closer in time to BGs taken to compare.

As a footnote it’s worth pointing out that others
using both systems have experienced occasions where there is a significant
difference between the number shown and the BG taken. I can only report on my
experience but I recommend reading other reviews for comparison.

Score: Libre 5/5
Enlite 4/5

Convenience

Libre

The convenience of wearing was a big plus for the
Libre. Whilst I knew it was there it wasn’t a pain at any point and it
certainly put up with a fair amount of knocks. To take a reading I needed to
pass the reader over the sensor. As this can be up between 1cm and 4cm away
from the sensor, wearing coats and jumpers didn’t cause any problems. Doing
this in public was unnoticeable and very quick to read. The downside is that as
a FGM during the night if I wanted a reading I’d need to find the reader, flash
and then find the number. Not hard but slightly more inconvenient than with the
Enlite.

Enlite

For some reason the design of the Enlite with a sensor
and transmitter seems to make the device a little more delicate and it certainly
doesn’t take knocks as well. A previous sensor was pushed off after only one
day and I’ve only just stopped crying at the expensive mistake that was! Out
and about use is really good though. The Veo looks like a pager with a wire so
checking a reading doesn’t look that strange and the backlight is helpful in dark
places. No need to flash means no unusual movements at all. Although as
mentioned above this wasn’t really a problem with the Libre. It did win on
middle of night checks though. As the Veo is a tubed pump finding it is always
fairly easy by starting at the site on my body and following the tube! After
that a quick button click for the light the check is complete. Much quicker
and easier.

Comparison

All in, both were good in parts.

Score: Libre 4/5
Enlite 4/5

Stickyness

Libre

This little beast stuck tight for me. Solid all week
and it needed a good tug on day 14 to yank it off. I’m sure it would have
lasted longer if the software would have let me. I went swimming and running
with no issues at all. Others have experienced some problems but not for me.

Enlite

This has always been a downside to the Enlite. After
much use I’ve now taken to using lots of clear tape on day 1 and this keeps it
secure for the duration. The nice marketing pictures show a lovely stomach with
only once piece of tape keeping it in place. I’d like to have seen it on day 6!

Comparison

A significant win for the Libre here due to only
needing the supplied underneath adhesive.

Score: Libre 5/5
Enlite 3/5

Availability

Libre

Currently licenced for over 18s only. I know there’s a
huge demand from the U18 market so hopefully the relevant licence isn’t too far
away

Enlite

Available for very small children upwards after
approval by their healthcare professional.

Score: Libre 4/5
Enlite 5/5

Overall

It would now be easy to count the marks in each
segment and declare a winner – don’t worry I will do that in a minute. But I
think that would miss the point here. We’re talking about two very different
systems that both manufacturers are keen to keep separate too.

The Enlite does what it’s designed for very well but
it’s limitations are that it needs a Medtronic Veo pump for it to be useful.
But when it does have one to link to the low glucose suspend and single reader factors are
huge pluses.

The Libre however can appeal to a much, much larger
market with MDI users being able to take advantage of the comparatively cheap
option to look at basal rates of long acting insulin and also insulin ratios
for short-acting. This is a huge market that CGM has always tried to get into
but struggled.

For me the design of the Libre is outstanding in that
it doesn’t look like a medical device and can sit securely under a sleeve (if
placed correctly!) totally out of site.

The speed of readings is a definite plus point but
with goodish hypo-awareness those six minutes become less significant although
still very, very impressive.

Ultimately the key factor in Veo users choosing one
over the other may come down to cost. I’ve previously talked about not being
able to justify funding the Enlite full-time and that’s still the case. The
Libre however is teasingly much cheaper. For full time use £1200 is a lot different to
£3600.

I’d hoped I’d be able to get to the bottom and make a
simple logical judgement on which is better. But I can’t. Yes the Libre wins by
49 points to 43 but where the Enlite wins on alerts and not needing to flash is
a huge factor.

So I think I’ll leave it to you to make your own mind
up on what’s most important to you and I’ll lob the ball into Medtronic’s court
to win me over with the new products they’ve got lined up in the coming months.

Game on!!

PS. Thanks for sticking to the end. It was a long one
but I hope you found it interesting.

Thanks Mike. I consider my blog pieces as a warm-up to your literary genius. I'm really looking forward to hearing you views on wearing it for a month to see if it affected your BG testing behaviour and whether it has encouraged you to buy any more.

Hi Geoff, sadly no. The Libre lives independently of any pump and won't transmit any data to it. The Enlite does (obviously) but again only to the Medtronic Veo pump. All these companies seem very closed when open communication would benefit us all.

Hi Dave just found your excellent blog thanks for the detailed comparison. I have been a type 1 diabetic for just under 40 years and take insulin through the pen, I have just started to pay just under £100 a month for the freestyle libre which has changed my life, Do you know what the costs are for minimed 670g for the CGM sensor only as the pump I can get from the NHS, If the sensors are too expensive do you know if you can use the Freestyle libre alongside the Minimum 670g pump. Many thanks. Kind Regards. Paul

The sensors used by the 640G (670G not available yet unfortunately) cost £55 per sensor and last 6 days (officially). To go with this you'll need a transmitter that costs £350 is guaranteed for 12 months.

At the moment I'm using the Libre alongside my pump so yes they can be used at the same time. However to take advantage of SmartGuard you'll need to use the Medtronic CGM system.

Disclaimer - please read!

I am not a medical professional in any way. Nothing on this site should be construed as medical advice. Your diabetes will vary. Contact your health care provider for specific questions and advice. Without sounding like a pharmaceutical company – do not change medication, dosage or philosophy without speaking to your DSN, doctor, consultant or witchdoctor.